As a catalyst for obtaining an α, β-unsaturated carboxylic acid through oxidation of an olefin or an α, β-unsaturated aldehyde in a liquid phase, a noble metal-containing catalyst has been known. For example, methods for producing an α, β-unsaturated carboxylic acid through oxidation of an olefin or an α, β-unsaturated aldehyde in a water-containing solvent in the presence of a silica-supported palladium-containing catalyst are disclosed in examples of Patent Document 1 and Patent Document 2.    Patent Document 1: International Publication No. WO 2005/075,072    Patent Document 2: International Publication No. WO 2005/118,134